The G11 appears in only available in the level "Numbers", where Dr. Clarke can be seen using it, however, while the player fires the G11 in three-round bursts, Clarke's seems to be fully automatic. Throughout Hong Kong, there are several G11s hidden both with and without the Low Power Scope in the multiple weapon caches Clarke has put around the city in fear of a Spetsnaz invasion.

The G11 is a classified assault rifle, meaning one has to buy every other assault rifle in order to unlock the weapon.

The G11 is a three-round burst weapon. The G11 is a three-hit kill up to 38 meters, and the damage gradually reduces to 25 up to 50 meters. The G11 is overall similar to the M16, although with a shorter range (the three-hit kill range of the M16 is 50 meters and the damage drops to 30 up to 63.5 meters), more hip-fire accuracy and a higher fire rate. As well, the G11's recoil sprays in a clockwise circle, while the M16's jumps upward. Considering the shorter range and lower damage, the G11 is more suited for close and medium range engagements, whereas the M16 is more suited for long range combats. In Hardcore, the G11 is a two-shot kill at long range whereas the M16 is a one-shot kill regardless of range, making the M16 better in Hardcore gamemodes.

The G11 uses 48-round magazine and fires a very quick three-round burst (1250 RPM per burst with a 200 milliseconds delay, resulting in 523 overall). It is more accurate than a submachine gun when firing from the hip, despite being an assault rifle and uses the same iron sights as the Famas, and the AUG.

The reload animation for the G11 varies from other assault rifles in-game, as the gun loads from a horizontal magazine using caseless ammunition. The G11 does not function like a traditional firearm; when picking up or reloading this weapon, the player rotates a knob near the rear of the weapon instead of pulling a charging handle. The G11 has a slow reload time for an assault rifle, making Sleight of Hand and/or reload cancelling advised.

The G11 has significantly larger ammo capacity than other assault rifles (48 compared to the next closest, Galil's 35 or 50 with Extended Mags), as well as more total ammo than any other weapon, even with Dual Mags (the Galil, M60, and MPL being the only exceptions; it ties the MPL's 192, and is only bested by the M60's 200-round belt and the Galil's 210 with Dual Mags). With the Variable Zoom Scope, the G11 is useful at extreme ranges in Hardcore game modes. Both the Variable Zoom and the Low Power Scope are also helpful in Hardcore gamemodes because at close to medium range, only one bullet is needed to kill, and the idle sway will make the three-round burst create a tight triangle of bullets rather than putting all three in the same spot, increasing the chances of a hit when one normally would have missed.

The G11 has a very bizarre set of attachments as it can only equip the unique Low Power Scope and the Variable Zoom available for sniper rifles. This makes Warlord completely redundant. Both attachments can help the player take more accurate shots at medium and longer ranges. It should also be noted that the Variable Zoom Scope is affected by Sleight of Hand Pro, since the G11 is not classified as a sniper rifle. Considering it has such a small hip-fire spread, comibining Steady Aim with the G11 can result in a powerful close-quarters weapon, although this might be overkill. The large magazine offers the ability to sustain a long-lasting stream of fire at close range, unlike most submachine guns and other assault rifles.

All in all, this rifle has significant advantages over the M16 that make it much more preferrable for fast-paced gameplay. But due to its lack of attachments, it may suffer from difficulties that an M16 would not encounter. For example, the added strategic advantages of underbarrel attachments like the Grenade Launcher or Masterkey are impossible to utilize with the G11. There are also no long range scopes that do not have idle sway, which, combined with the lower damage, may disadvantage the player at long range.

The G11 is a fairly underpowered weapon in Zombies. The G11's strong suit it its accuracy, allowing the player to accurately take shots at zombies with its low recoil and the scope's low idle sway. However the G11 has a low damage per shot, and the G11 tends to become weak around round 15 as its low damage to the body can leave the player vulnerable in between bursts.

When Pack-A-Punched, it becomes the G115 Generator, which is a reference to Element 115. It becomes fully automatic and still features the Low Power Scope, but with no sway, also the reloads are sped up by half a second. Even when firing on full-auto at 1250 RPM, it still retains its low recoil making it more useful in close-quarter situations with its extremely high fire rate. Double Tap Root Beer is strongly inadvisable because ammo will run short within a round, but Speed Cola is a very good choice as the G115 Generator will burn through a lot of ammo and the reload time is relatively long.